Sub test()
    Dim lngLeft   As Long
    Dim lngTop    As Long
    Dim lngRight As Long
    Dim lngBottom As Long
    Dim objShape As Object

    ' セル範囲の座標取得
    With Range("A1:F20")
        lngTop = .Top
        lngLeft = .Left
        lngBottom = .Top + .Height
        lngRight = .Left + .Width
    End With
    ' アクティブシートの図形列挙
    For Each objShape In ActiveSheet.DrawingObjects
        ' 範囲内にあるかチェック
        With objShape
            If lngTop <= .Top And lngLeft <= .Left And _
               lngBottom >= .Top + .Height And lngRight >= .Left + .Width Then
                ' 範囲内にあれば削除
                .Delete
            End If
        End With
    Next
End Sub